Bring in line with the key from billing_monthly_cronjob
Merge branch 'low-balance-auto-top-up' * low-balance-auto-top-up: Some people have exactly 5 who don't need to be told On low balance, top-up or notify ExpiringLock helper
ExpiringLock helper For things we want to do only so often, set up a helper to push expiring keys to Redis and check for them.